The present invention relates to a television receiver for controlling programmable signal processing adaptively corresponding to various signal formats by using a CPU.
In a conventional NTSC system television receiver, various picture quality corrections and setting are done, such as sharpness and gradation of luminance signal (Y) and color saturation of chroma signal (C) separated from NTSC composite signal by Y/C separation circuit, or functions for changeover of video input and on-screen display are provided for the request or convenience of the user.
However, the specifications of the television receiver requested by the users are becoming more and more sophisticated in the recent trend of multimedia, and numerous models must be developed to cope with these requests adequately. It is a subject for television receiver manufacturers to develop many models of television receivers differing in part of processing functions while maintaining common processing functions depending on the requests.
If a specification change or additional function occurs in a television receiver, it is hard to change the circuit composition according to the specification change of the receiver because the circuit composition of television receiver is realized by optimization. On the other hand, if more functions than necessary are incorporated in the television receiver, functions not needed by the user are built in the receiver, and the price of the receiver becomes higher.
Or when extending the functions of the television receiver, since the additional functions are diverse, the interface types of the additional function units and the internal circuit of the television receiver are also diverse, and plural interface circuits may be accommodated.
Still more, when the user of the television receiver connecting such units for extending the additional functions further desires functional changes of the additional function extension units by change of condition of use or the like, change or modification of the additional function extension units is required again, and it causes much labor and cost. At the same time, the content of the memory incorporated in the receiver must be changed.